Method of condensing zinc vapors



1,535,252 O. RAVNER METHOD oF CONDENSING ZINC vAPoRs Filed Feb. 24, 1919 3 Sheets-Sheet l y Way/lll] April 28, 1925. 1,535,252

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UNITED STATESPATENT or '1,535,252 FICE.

OYSTEIN RAVNER, OF CHRISTIANIA, NORWAY, 'ASSIG'NOR T0 DET N ORSKE AKTIESEL- SKAB FOR ELEKTROKEMISK INDUSTRIE, 0F CHRISTIANIA, NORWAY, A. BUSINESS ENTITY, 0F CHRISTIANIA, NORWAY.

METHOD OF CONDENSING ZINC VAPORS.

p Application tiled February 24, 1919. Serial No. 278,977.

To alZ 'whom it may conce'm:

Be it known that I, OYSTEIN RAVNER, a subject of Norway, and a resident of Chris- 'tiania, Kingdom of Norway, have invented certain new and useful Improvements in the Methods of Condensing Zinc Vapors, of which the following is a specification.

This invention relates to the production of metallic zinc and has for its object a method whereby zinc may be recovered from its ores in a continuous process with great economy and with a comparatively small loss of metal vin the form of zinc dust.

In the electrotherrnicl processes hitherto known for the production of zinc the gases have for the most part been led from the distillation chamber through comparativelyV long, vertical condensation channels to a receptacle for the condensed product. During their passage through these channels the gases have gradually cooled and a separation of carbon monoxide gas and zinc vapors has to some extent taken lace.

Such methods of working facilitate the formation of fogl and oxidation of the metal -due to the influence of CO2 formed bydecomposition of CO according to the equation Contrary to such practicevI avoid the disadvantages mentioned by subjecting the gases from the furnace to an intense and sudden cooling, thus causing the gases to pass rapid- "ly that interval of temperature in which the transformation of CO to CO2 and conseuently oxidation of zinc may take place. ils a result hereof and also due to the comparatively small size of the condensing surface needed whenv such intense cooling is used,v the formation of zinc dust is reduced to a minimum. s

I have found that undercertain conditions it may be advantageousnot only to apply intense cooling to that part of the condensation channel which is nearest to the distillation chamber but also to cool the rest of the channel whereby the total condensing surface may be further reduced.

Further I have found that intense cooling and' reduced condensing surface tend to favor the .formation of greater drops ofy liquid metal than would be obtained by the usual slow cooling, and these drops will during their fall through the gas cause a' precipitation of the fine particles forming a fog. Thus by my method of working, condltions are favorable for a rapid and effective separation of metal vapor from accompanying carbon monoxide gas.

As will be understood from above remarks, my process may be carried out in many different ways. It is especially suitable" for the production of zinc but ma also be used for other metals of similar qua ities.

The furnace construction may be of any well known type as my present invention only deals with the treatment of the gases and vapors escaping from the furnace.A As a rule, however, an electric furnace will be preferable.

The above described sudden cooling of the l any suitable type I companying drawings forming part of this application. Figures 1, 2 and 3 represent dierent modifications-of my invention. In

Figure l the numeral 1 designates an electric zinc furnace, and 2 an outlet for the gases formed in the furnace. These are led through a channel provided with a cooling arrangement 3, with inlet for water at 4, and outlet at 5. The furnace gases are by means of this arrangement rapidly cooled down4 below 700 C. at which temperature the velocity of the reaction QCCZCOZ-l-C is not great., The channel isat 6 divided in two branches one upper and one lower. lIt may further be provided with obstacles for the gases so as to facilitatevthe formationof great drops, which when falling-through the channel precipitate the finest zinc particles otherwisetending to'form a fog. As the channel is divided the velocity of the g gases' will consequently be reduced and the which at the prevailremaining zinc' vapor, ing tempera-ture does not follow the -gaslaws but is a. saturated vapor, will separate out from the accompanying ideal carbon monoxide, and follow the Alower gas,

. on similar parts,

`with the receptacle 9 serves branch of the channel to a closed receptacle 9, while the said ideal gas having the greater buoyancy will ascend the upper branch 7 of the channel. 4'The separation is of course not complete and some zinc vapors will follow the upper branchv 7, which is provided having a grate 10, with movable bars. On this grate is placed coke or other filtering material, which when the bars are t-urned gradually falls into the receptacle 9 and is removed therefrom together with the zinc dust which may have been formed.

The chimney above the grate 10 is provided with a cooler 11 and an outlet 8 for carbon monoxide. The outlet may be provided with a water lock in order to keep the system under slight pressure.

The vapor rising through the branch 7, will either become condensed therein or on the filtering material in the form of metallic zinc or zinc dust. The free condensed product will fall back into the lower-channel and the receptacle 9, while that retained byl the filterin material may be removed therewith, as a ove set forth. If coke or a similar material is employed it may advantageously be used as the reduction agent in the electric zinc furnace, thus utilizing and recovering the zinc contained in the filtering material.

The lower branch of the channel together the purpose of collecting the total amount of zinc condensed and also of condensing the remaining zinc vapor. As the receptacle is a closed vessel, except-for thel entrance port of the -lower branch of the channel, carbon monoxide which may enter the vessel cannot pass through, but will be pressed back intothe lower channel.

The zinc dust which is formed during the process may advantageously be subjected to a mechanic'al action to break up the oxide-film, formed on each particle, so that the particles when free therefrom will melt together. In order to obtain this effect the receptacle may be constructed as a movable or rotating cylinder and may by means of a heatingr or a cooling arrangement tnot shown in the drawing) be kept at a temperature suitable for this mechanical treatment of the zinc dust.

Figures 2 and 3- represent slightly modified examples of my invention, the same referencevnumerals as in Fig. 1 being employed with primes affixed where the' parts have been slightly modified. In Figure 2 the arrangement is mainly the same as in Figure 1 excepting that the gas channel throughout its whole length is provided with water cooling means 3, and that the part-of the channel between the furnace and the pomt where the two branches separate is given a gradually increasing cross section in order to reduce the speed ofthe gases' and facilitate the separation of metal vapor and as. In addition obstacles 19 are provide upon the upper wall of the channel to further condensation and assure the dripping of liquid metal across the current of metal vapor and dust.

In the example illustrated by Fi re 3 the furnace is connected with a cham r 13 through the openin 12. The chamber 13 has at its upper en an outlet 14 for noncondensible gases and is at its lower end connected with the closed receptacle 15.

Above the outlet 12 there are placed coolers 16, the lower side of which is provided with obstacles 17 on which zinc may be condensed. The drops may then fall through the chamber thus precipitating the fog already formed. A grate 18 with movable bars on which filtering material is placed, isarranged above the coolers.

From the a'bove it will be observed that the channel itself together with its branches serves as a condensation chamber.

The foregoing detailed description has been given for clearness of understanding and no undue limitation should be deduced therefrom, but the apprehended claims should be construed as broadly as permissi-l ble in view of the prior art.

What I claim as new and desire to secure by Letters Patent of the United States 1s:

1. The process of recovering metals from hot vapors thereof, which comprises leading the vapors from the furnace in which they are formed directly into a condensation chamber and subjecting the vapors to immediate and intense cooling,` liquefying portions of the vapor in the form of drops, and effecting precipitation of metal dust resulting from the condensation by passing thesaid liquid metal drops therethrough in opposing direction to the flow thereof.

2. The process of recovering metals from hot vapors thereof in an atmosphere of carbon monoxide, which comprises leading the gas and vapors from the furnace in which 'they are formed directly into a condensation chamber and immediately lowering the temperature of the gas and vapors to a point below that at which carbon dioxide is readily formed, whereby oxidation of thel metal is substantially-prevented.

3. The process of recovering metals from hot vapors thereof in an atmosphere of carbon monoxide, which comprises leading the gas and vapors from the furnace in which they are formed directly into a condensation chamber and immediately lowering the temperature of the gas and vapors to a point below 700 C., whereby oxidation of the metal is substantially prevented.

4. The process of recovering metals from hot vapors thereof in a gaseous atmosphere,

which comprises leading the gas and vapors from the furnace inv which they are formed directly into a condensation chamber and subjecting the gas and vapors to immediate and intense cooling thus effecting a partial condensation of the metal vapor, dividing the gas and remaining vapors into an upper current and a lower current, interposing in the upper'.current a filtering medium for additional condensation, and collecting the condensed metal in part on the said filtering material and in part in a receptacle into which the said lower currentis directed.

V5. The process of removing metals from hot vapors thereof, which comprises leading the vapors from the furnace in which they are formed directly into a condensation chamber and subjecting the vapors to immediate and intense cooling whereby oxida- -4 tion of the'metal is substantially prevented and the vapor is condensed in part in liquid form and in part as film-covered dust particles, and subjecting the film-covered dust particles to mechanical actionwhereby the film is removed and the dust particles are fused into liquid form.

Signed atcChristiania,Norway, this 19th vday of December, 1918.

OYSTEIN RAVNER. 

